2 Answers
2

First, it would help to know if your app is going to be a Canvas app or not. Canvas apps can be as wide as the browser will allow and non-canvas apps are 810px wide. In both cases, apps will allow the content area to grow, meaning the canvas will resize itself to fit your content and removing the need for scrollbars within the app.

I don't suggest using vertical scrollbars within an app frame. If the app frame height is greater than the browser window height, then once you've scrolled to the bottom of the app frame you'll start scrolling the page. This can be especially annoying once you start to scroll back up.